Helm intro

Get the cluster running

# start you local minikube cluster
minikube start

# check that the cluster is running with
minikube status
kubectl get ns  # ns is shorthand for namespace

Deploy your first chart

# create the namespace for the chart
kubectl create ns helm-intro

# install the given chart into the helm-intro namespace
helm install intro . -f values.yaml -n helm-intro

This installed the REVISION: 1 of this chart under the name intro (that can be choosen) and returned the content of the file templates/NOTES.txt with some notes for the user.

There are a few ways to look at the revision now.

# get the manifests currently deployed
helm get manifest intro -n helm-intro

# analyze a specific helm revision
helm status intro -n helm-intro -o yaml --revision 1

Now let's checkout the app we've deployed. In templates/deployment.yaml a deployment is defined with a pod template for a default nginx server. In templates/service.yaml there is a service called nginx-service exposing the pod on a node port. In templates/configmap.yaml there is the index.html page replacing the nginx default (mounted in the deployment).

# minikube has this neat way of getting the url for the service
minikube service nginx-service --url -n helm-intro

Let's see if there is Welcome to the helm intro! on this url and whether it looks very much green.

Upgrade the chart

Seems like the designer thinks fuchsia seems to a better color 😱, let's change the nginx backgroundColor in values.yaml to fuchsia.

To verify the change before upgrading this chart now, you can use this super cool plugin to check what's gonna happen.

# download the plugin (this will simply place the repo into
# a helm plugin directory)
helm plugin install https://github.com/databus23/helm-diff

# let's use the plugin to see what would happen if we were
# to upgrade this chart
helm diff upgrade intro . -n helm-intro -f values.yaml

Looks good, right? Only the background color changed in our configmap plus the checksum in the deployment annotations. Time to actually do the change.

helm upgrade intro . -n helm-intro -f values.yaml

To check what happend between revision 1 and 2, let's use this awesome plugin again!

helm diff revision -n helm-intro intro 1 2

Rollback

Oh snap! Fuchsia looks terrible 😋. Let's rollback, but check the diff in advance - just to be sure...

# diff for the rollback from the current revision 2 to the revision 1
helm diff rollback -n helm-intro intro 1

This looks good, rolling back will again set the color to green. Let's go with that change and rollback the release.

helm rollback -n helm-intro intro 1

The history shows now also that the revision 3 was a rollback to revision 1.

helm history -n helm-intro intro

Destroy everything

Let's get rid of that stuff, enough is enough:

# uninstall the chart
helm uninstall -n helm-intro intro

# remove the namespace
kubectl delete ns helm-intro

# delete the minikube cluster
minikube delete